package org.bouncycastle.asn1.cms;

import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Primitive;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERSequence;

/**
 * <a href="https://tools.ietf.org/html/rfc5652#section-6.2.2">RFC 5652</a>:
 * Content encryption key delivery mechanisms.
 *  
 * RecipientEncryptedKey ::= SEQUENCE {
 *     rid KeyAgreeRecipientIdentifier,
 *     encryptedKey EncryptedKey
 * }
 * </pre>
 */
public class RecipientEncryptedKey
    extends ASN1Object
{
    private KeyAgreeRecipientIdentifier identifier;
    private ASN1OctetString encryptedKey;

    private RecipientEncryptedKey(
        ASN1Sequence seq)
    {
        if (seq.size() < 2)
        {
            throw new IllegalArgumentException("expected sequence size of 2");
        }

        identifier = KeyAgreeRecipientIdentifier.getInstance(seq.getObjectAt(0));
        encryptedKey = (ASN1OctetString)seq.getObjectAt(1);
    }

    /**
     * Return an RecipientEncryptedKey object from a tagged object.
     *
     * @param obj the tagged object holding the object we want.
     * @param explicit true if the object is meant to be explicitly
     *              tagged false otherwise.
     * @exception IllegalArgumentException if the object held by the
     *          tagged object cannot be converted.
     */
    public static RecipientEncryptedKey getInstance(
        ASN1TaggedObject    obj,
        boolean             explicit)
    {
        return getInstance(ASN1Sequence.getInstance(obj, explicit));
    }

    /**
     * Return a RecipientEncryptedKey object from the given object.
     * <p>
     * Accepted inputs:
     *  
     *   null &rarr; null
     *   {@link RecipientEncryptedKey} object
     *   {@link org.bouncycastle.asn1.ASN1Sequence#getInstance(java.lang.Object) ASN1Sequence} input formats with RecipientEncryptedKey structure inside
     * </ul>
     *
     * @param obj the object we want converted.
     * @exception IllegalArgumentException if the object cannot be converted.
     */
    public static RecipientEncryptedKey getInstance(
        Object obj)
    {
        if (obj instanceof RecipientEncryptedKey)
        {
            return (RecipientEncryptedKey)obj;
        }

        if (obj != null)
        {
            return new RecipientEncryptedKey(ASN1Sequence.getInstance(obj));
        }

        return null;
    }

    public RecipientEncryptedKey(
        KeyAgreeRecipientIdentifier id,
        ASN1OctetString             encryptedKey)
    {
        this.identifier = id;
        this.encryptedKey = encryptedKey;
    }

    public KeyAgreeRecipientIdentifier getIdentifier()
    {
        return identifier;
    }

    public ASN1OctetString getEncryptedKey()
    {
        return encryptedKey;
    }

    /**
     * Produce an object suitable for an ASN1OutputStream.
     */
    public ASN1Primitive toASN1Primitive()
    {
        return new DERSequence(identifier, encryptedKey);
    }
}
